Substituted pyrimidine compounds and the use thereof

ABSTRACT

The present invention relates to the use of pyrimidine compounds of the following formula:                    
     where R 1 , R 2 , R 3 , A, B and Ar have the meanings indicated in the description. The compounds according to the invention have a high affinity for the dopamine D 3  receptor and can therefore be used to treat disorders which respond to dopamine D 3  ligands.

This is a Divisional application of application Ser. No. 08/765,292, filed on Jan. 14, 1997, under Section 371 which is U.S. Pat. No. 6,342,604

The invention relates to substituted pyrialidine compounds and to the use of such compounds. Said compounds have valuable therapeutic properties and can be used in particular to treat disorders which respond to dopamine D₃ ligands.

Compounds which are of the type under discussion here and have physiological activity have in some cases been disclosed. Thus, DE 21 39 082 and DE 22 58 561 describe pyrimidine derivatives and pyrimidone derivatives with basic substituents as drugs for lowering blood pressure. These pyrimidine and pyrimidone derivatives have the formulae:

where in (A) X is, inter alia, sulfur, A is C₁-C₆-alkylene, and R¹, R², R³ and Z are various substituents. In (B), X and Y are each oxygen or sulfur, A is C₂-C₆-alkylene and R and Z are various substituents.

Neurons receive their information inter alia via G protein-coupled receptors. There are numerous substances which exert their effect via these receptors. One of them is dopamine.

Confirmed findings on the presence of dopamine and its physiological function as neurotransmitter have been published. Cells which respond to dopamine are connected with the etiology of schizophrenia and Parkinson's disease. These and other disorders are treated with drugs which interact with dopamine receptors.

By 1990, two subtypes of dopamine receptors had been clearly defined pharmacologically, namely D₁ and D₂ receptors.

Sokoloff et al., Nature 1990, 347: 146-151, found a third subtype, namely D₃ receptors. They are expressed mainly in the limbic system. The D₃ receptors differ structurally from the D₁ and D₂ receptors in about half the amino-acid residues.

The effect of neuroleptics has generally been ascribed to their affinity for D₂ receptors. Recent receptor-binding studies have confirmed this. According to these, most dopamine antagonists, like neuroleptics, have high affinity for D₂ receptors but only low affinity for D₃ receptors.

We have now found, surprisingly, that certain pyrimidine compounds have a high affinity for the dopamine D₃ receptor and a low affinity for the D₂ receptor. They are thus selective D₃ ligands.

The present invention therefore relates to the use of pyrimidine compounds of the general formula I:

where

A is C₁-C₁₈-alkylene which may comprise at least one group selected from O, S, NR⁴, CONR⁴, NR⁴CO, COO, OCO and a double or triple bond,

B is

R¹, R², R³ are selected, independently of one another, from H, halogen, OR⁴, NR⁴R⁵, SR⁴, CF₃, CN, CO₂R⁴ and C₁-C₈-alkyl which is unsubstituted or substituted by OR, OC₁-C₈-alkyl or halogen,

R⁴ is H, C₁-C₈-alkyl which is unsubstituted or substituted by OR, OC₁-C₈-alkyl or halogen,

R⁵ has the meanings indicated for R⁴ or is COR⁴ or CO₂R⁴;

Ar is phenyl, pyridyl, pyrimidyl or triazinyl, where Ar may have from one to four substituents which are selected, independently of one another, from OR⁵, C₁-C₈-alkyl, C₂-C₆-alkenyl, C₂-C₆-alkynyl, halogen, CN, CO₂R⁴ ₁, NO₂, SO₂R⁴, SO₃R⁴, NR⁴R⁵, SO₂NR⁴R⁵, SR⁴, CF₃, CHF₂, a 5- or 6-membered carbocyclic aromatic or non-aromatic ring and a 5- or 6-membered heterocyclic aromatic or non-aromatic ring having 1 to 3 hetero atoms which are selected from O, S and N, where the ring may be unsubstituted or substituted by C₁-C₈-alkyl, Hal, OC₁-C₈-alkyl, OH, NO₂, CF₃, and where Ar may also be fused to a carbocyclic or heterocyclic ring of the type defined above, and the salts thereof with physiologically tolerated acids for producing a pharmaceutical composition for treating disorders which respond to dopamine D₃ receptor antagonists or agonists.

The invention also relates to the pyrimidine compounds of the formula I′

where

A, B, Ar, R¹, R² and R³ have the meanings stated in claims 1 to 8, and the salts thereof with physiologically tolerated acids, excepting the compounds of the formula

where R¹ is OH or SH, R² and R³ are, independently of one another, H, C₁-C₈-alkyl, OC₁-C₆-alkyl, SC₁-C₆-alkyl, CO₂H, OH, SH, NR⁴R⁵ or halogen, where R⁴ and R⁵ are H or C₁-C₆-alkyl, A is SC₁-C₆-alkylene, NHC₁-C₆-alkylene or N(C₁-C₆-alkyl)-C₁-C₆-alkylene, B is

 and Ar is phenyl

which may have one or more substituents selected from C₁-C₄-alkyl, OC₁-C₄-alkyl, SC₁-C₄-alkyl, NO₂, CF₃, F, Cl or Br.

The compounds used according to the invention are selective dopamine D₃ receptor ligands which intervene regioselectively in the limbic system and, because of their low affinity for the D₂ receptor, have fewer side effects than classical neuroleptics, which are D₂ receptor antagonists. The compounds can therefore be used to treat disorders which respond to dopamine D₃ receptor antagonists or agonists, eg. for treating disorders of the central nervous system, in particular schizophrenia, depression, neuroses and psychoses. They can additionally be used to treat sleep disorders and nausea and as antihistamines.

Within the scope of the present invention, the following terms have the meanings indicated below: alkyl (also in radicals such as alkoxy, alkylamino, etc.) means a straight-chain or branched alkyl group having 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms and, in particular, 1 to 4 carbon atoms. The alkyl group can have one or more substituents which are selected, independently of one another, from OH and OC₁-C₈-alkyl.

Examples of an alkyl group are methyl, ethyl, n-propyl, i-propyl, n-butyl, isobutyl, t-butyl, etc.

Alkylene stands for straight-chain or branched radicals having, preferably, 2 to 15 carbon atoms, particularly preferably 3 to 10 carbon atoms.

The alkylene groups may comprise at least one of the abovementioned groups. This can—just like the double or triple bond mentioned—be arranged in the alkylene chain at any point or at the end of the chain so that it connects the chain to the pyrimidine residue. The latter is preferred. When the alkylene group comprises a double or triple bond, it has at least three carbon atoms in the chain.

Halogen is F, Cl, Br, I and, in particular, Cl, Br, I.

R¹, R² and R³ are preferably, independently of one another, H, C₁-C₈-alkyl, NR⁴R⁵, SR⁴ or OR⁴, where R⁴ and R⁵ are, independently of one another, H or C₁-C₈-alkyl.

Ar can have one, two, three or four substituents, preferably one or two substituents, which are in each case in the m position. They are preferably selected independently from halogen, CF₃, CHF₂, CN, NO₂, OR⁴, NR⁴R⁵, C₁-C₈-alkyl, OC₁-C₈-alkyl, phenyl and SR⁴, where R⁴ and R⁵ are H or C₁-C₈-alkyl. If one of the substituents is C₁-C₈-alkyl, a branched group and, in particular, isopropyl or t-butyl is preferred.

Ar preferably has at least one substituent and is, in particular,

where D¹, D² and D³ are, independently of one another, CR or N, and R, S and Y are H or have the meanings indicated above or below.

Ar is preferably unsubstituted or substituted phenyl, 2-, 3- or 4-pyridinyl or 2-, 4(6)- or 5-pyrimidinyl.

When one of the substituents of the radical Ar is a 5- or 6-membered heterocyclic ring, examples thereof are a pyrrolidine, piperidine, morpholine, piperazine, pyridine, 1,4-dihydropyridine, pyrimidine, triazine, pyrrole, thiophene, thiazole, imidazole, oxazole, isoxazole, pyrazole or thiadiazole residue.

When one of the sustituents of the radical Ar is a carbocyclic radical, it is, in particular, a phenyl, cyclopentyl or cyclohexyl radical.

When Ar is fused to a carbocyclic or heterocyclic radical, it is, in particular, a naphthalene, di- or tetrahydronaphthalene, quinoline, di- or tetrahydroquinoline, indole, dihydroindole, benzimidazole, benzothiazole, benzothiadiazole, benzopyrrole or benzotriazole residue.

A preferred embodiment comprises the compounds of the formula I where A is C₁-C₁₀-alkylene which may comprise at least one group selected from O, S, NR³, cyclohexylene and a double or triple bond.

Another preferred embodiment comprises use of the compounds of the formula I where R¹, R² and R³ are, independently of one another, H, C₁-C₈-alkyl which can be unsubstituted or substituted by OH, OC₁-C₈-alkyl or OH [sic], or OH, OC₁-C₈-alkyl, SR⁴ or NR⁴R⁵, where R⁴ and R⁵ are, independently of one another, H or C₁-C₈-alkyl;

Ar is phenyl, pyridyl or pyrimidyl which may have one, two, three or four substituents selected from H. C₁-C₈-alkyl which may be substituted by OH, OC₁-C₈-alkyl or halogen, or OR⁴ where R⁴ is , C₁-C₈-alkyl which may be substituted by OH, OC₁-C₈-alkyl or halogen, or CHF₂, CF₃, CN, halogen, C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₁-C₆-cyclohexyl [sic], phenyl, naphthyl and a 5- or 6-membered heterocyclic aromatic radical with 1 to 3 hetero atoms selected from O, N and S.

Another preferred embodiment comprises use of the compounds of the formula I where B is

Another preferred embodiment is the use of the compounds of the formula I where Ar is phenyl which has one to four substituents which are selected, independently of one another, from H, C₁-C₈-alkyl which may be substituted by OH, OC₁-C₈-alkyl or halogen, or phenyl, naphthyl, pyrrolyl, CN, NO₂, CF₃, CHF₂, halogen, SO₂R⁴ or SR⁴ where R⁴ is H or C₁-C₈-alkyl, or where the substituents are selected, independently of one another, from C₁-C₈-alkyl, phenyl, CF₃, CHF₂, CN, NO₂, halogen, OC₁-C₈-alkyl or SR⁴ where R⁴ is H or C₁-C₈-alkyl, and Y is H, C₁-C₈-alkyl, Hal or CF₃.

Another preferred embodiment is the use of compounds of the formula I where Ar is pyrimidinyl which has one to three substituents which are selected, independently of one another, from H, C₁-C₈-alkyl, phenyl, naphthyl, C₃-C₆-cyclohexyl [sic], OH, OC₁-C₈-alkyl, halogen, CN, NO₂, CF₃, CHF₂ and a 5- or 6-membered heterocyclic aromatic or non-aromatic radical with 1 to 3 hetero atoms selected from O, N and S.

Another preferred embodiment is the use of compounds of the formula I where Ar is pyridinyl which has one to four substituents which are selected, independently of one another, from H, C₁-C₈-alkyl, phenyl, naphthyl, OH, OC₁-C₈-alkyl, halogen, CF₃, CN, C₂-C₆-alkenyl, C₂-C₆-alkynyl and a 5- or 6-membered heterocyclic aromatic radical with 1 to 3 hetero atoms selected from O, N and S.

The invention also embraces the acid addition salts of the compounds of the formula I with physiologically tolerated acids. Examples of suitable physiologically tolerated organic and inorganic acids are hydrochloric acid, hydrobromic acid, phosphoric acid, sulfuric acid, oxalic acid, maleic acid, fumaric acid, lactic acid, tartaric acid, adipic acid or benzoic acid. Other acids which can be used are described in Fortschritte der Arzneimittelforschung, Volume 10, pages 224 et seq., Birkhauser Verlag, Basle and Stuttgart, 1966.

The compounds of the formulae [sic] I may have one or more centers of asymmetry. The invention therefore includes not only the racemates but also the relevant enantiomers and diastereomers. The invention also includes the tautomeric forms in each case.

The compounds of the formula I′ can be prepared by methods similar to conventional ones as described, for example, in A. R. Katritzky, C. W. Rees (ed.), “Comprehensive Heterocyclic Chemistry”, 1st Edition, Pergamon Press 1984, in particular Vol. 3, Part 2A; D. J. Brown “The Pyrimidines”, in “The Chemistry of Heterocyclic Compounds”, E. C. Taylor (ed.), John Wiley & Sons Inc. NY, in particular Vol. 16+Suppl. I+II (1985) and Vol 52 (1994) and literature cited therein. The process for preparing the compounds comprises

i) reacting a compound of the general formula II:

where Y¹ is a conventional leaving group, with a compound of the general formula III

H—B—Ar;

ii) to prepare a compound of the formula I′ where A is oxygen or sulfur or NR⁴:

reacting a compound of the general formula IV:

where Z¹ is O, S or NR , and A¹ is C₀-C₁₈-alkylene, with a compound of the general formula VI

Y¹—A²—B—Ar

where Y¹ has the abovementioned meanings, and A² is C₁-C₁₈-alkylene, where A¹ and A² together have 1 to 18 carbon atoms,

iii) to prepare a compound of the formula I′ where A comprises the group COO or CONR⁴:

reacting a compound of the general formula VII:

or a salt thereof, where Y² is OH, OC₁-C₄-alkyl, Cl or, together with CO, is an activated ester group, and A¹ has the abovementioned meanings, with a compound of the formula VIII:

Z¹—A²—B—Ar

where A² has the abovementioned meanings, and Z¹ is OH or NHR⁴,

iv) to prepare a compound of the formula I′ where A comprises the group OCO or NR⁴CO:

reacting a compound of the formula IV

where Z¹ is C or NR⁴, with a compound of the formula X:

Y²CO—A²—B—Ar

where A², B and Y² have the abovementioned meanings, is and where R¹, R², R³, A, B and Ar have the above-mentioned meanings.

The reactions described above generally take place in a solvent at from room temperature to the boiling point of the solvent used. Examples of solvents which can be used are ethyl acetate, tetrahydrofuran, dimethylformamide, dimethoxyethane, toluene, xylene or a ketone, such as acetone or methyl ethyl ketone.

An acid acceptor is present if required. Suitable acid acceptor s are inorganic bases such as sodium or potassium carbonate, sodium methoxide, sodium ethoxide, sodium hydride or organic bases such as triethylamine or pyridine. The latter can also serve as solvents.

The crude product is isolated in a conventional way, for example by filtration, removal of the solvent by distillation or extraction from the reaction mixture, etc. The resulting compound can be purified in a conventional way, for example by recrystallization from a solvent, chromatography or conversion into an acid addition compound.

The acid addition salts are prepared in a conventional way by mixing the free base with the appropriate acid, possibly in solution in an organic solvent, for example a lower alcohol such a methanol, ethanol or propanol, an ether such as methyl t-butyl ether, a ketone such as acetone or methyl ethyl ketone, or an ester such as ethyl acetate.

The abovementioned starting materials are disclosed in the literature or can be prepared by known processes.

To treat the abovementioned disorders, the compounds according to the invention are administered in a conventional manner orally or parenterally (subcutaneously, intravenously, intramuscularly, intraperitoneally). Administration can also take place with vapors or sprays through the nasopharyngeal space.

The dosage depends on the age, condition and weight of the patient and on the mode of administration. As a rule, the daily dose of active substance is about 10 to 1000 mg per patient and day on oral administration and about 1 to 500 mg per patient and day on parenteral administration.

The invention also relates to pharmaceutical compositions which contain the compounds according to the invention. These compositions are in the usual solid or liquid pharmaceutical administration forms, for example as tablets, film-coated tablets, capsules, powders, granules, sugar-coated tablets, suppositories, solutions or sprays. The active substances can in these cases be processed with conventional pharmaceutical aids such as tablet binders, fillers, preservatives, tablet disintegrants, flow regulators, plasticizers, wetting agents, dispersants, emulsifiers, solvents, release-slowing agents, antioxidants and/or propellant gases (cf. H. Sucker et al., Pharmazeutische Technologie, Thieme-Verlag, Stuttgart, 1978). The administration forms obtained in this way normally contain the active substance in an amount from 1 to 99% by weight.

The following examples serve to explain the invention without limiting it.

EXAMPLE 1 4-[3-(4-{3-Trifluoromethylphenyl}piperazinyl)propylthio]pyrimidine

a) 1-(3-Chlorophenyl) -4-(3-trifluoromethylphenyl)piperazine

30 g (0.13 mol) of m-trifluoromethylphenylpiperazine, 23 g (0.146 mol) of 1-bromo-3-chloropropane and 15 g (0.148 mol) of triethylamine in 200 ml of THF were refluxed for 4 hours. Cooling was followed by filtration with suction and concentration. The viscous residue was taken up in ethyl acetate, washed with water, dried over MgSO₄ and then concentrated. The residue comprised 39 g of product as a yellowish oil (quantitative yield).

b) 4-[3-(4-{3-Trifluoromethylphenyl}piperazinyl)propylthio]pyrimidine

1.5 g (13.4 mmol) of 4-mercaptopyrimidine, 4.3 g (14 mmol) of 1-(3-chloropropyl)-4-(3-trifluoromethylphenyl)piperazine and 1.5 g (15 mmol) of triethylamine in 5 ml of DMF were stirred at 100° C. for 1 hour. The mixture was then poured into 5% strength hydrochloric acid and extracted with MTB ether. The aqueous phase was made alkaline with sodium hydroxide solution and then extracted with ethyl acetate, and the organic phase was dried over MgSO₄ and concentrated. The residue was purified by chromatography (mobile phase: CH₂Cl₂/CH₃OH=98/2). 3.0 g of product were obtained as a yellowish oil (=59% yield).

H-NMR [δ, ppm]: 1.95 (2H); 2.55 (2H); 2.65 (4H); 3.25 (6H); 7.06 (3H); 7.15 (1H); 7.35 (1H); 8.33 (1H); 8.9 (1H).

EXAMPLE 2 2-(5-(4-{3-Trifluoromethylphenyl}piperazinyl)pentylmercaptolpyrimidine

a) 2-(5-Chloropentylmercapto)pyrimidine

2.8 g (25=mol) of 2-mercaptopyrimidine, 4.64 g (25 mmol) of 1-bromo-5-chloropentane and 2.58 g (25.5 mmol) of triethylamine in 100 ml of THF were refluxed for 4 hours. After cooling, filtration with suction and concentration, the residue was purified by chromatography (mobile phase: cyclohexane/ethyl acetate=92/8). 2.8 g of product were obtained (=52% yield).

b) 2-[5-(4-{3-Trifluoromethylphenyl}piperazinyl)pentylmercapto]pyrimidine

2.8 g (12.9 mmol) of 2-(5-chloropentylmercapto)pyrimidine, 3.27 g (14.2 mmol) of m-trifluoromethylphenylpiperazine and 1.44 g (14.2 mmol) of triethylamine in 5 ml of DMF were stirred at 90° C. for 1 hour. The mixture was then poured onto water and extracted three times with CH₂Cl₂, and the extracts were dried over MgSO₄ and concentrated. The residue was mixed with methyl t-butyl ether and filtered with suction, and the mother liquor was concentrated. Purification by chromatography (mobile phase: CH₂Cl₂/CH₃OH=97/3) resulted in 4.0 g of product as oil (=75% yield).

H-NMR [δ, ppm]: 1.54 (4H); 1.78 (2H); 2.4 (2H); 2.6 (4H); 3.18 (2H); 3.23 (4H); 6.95 (1H); 7.01 (3H); 7.1 (3H); 7.33 (1H); 8.5 (1H).

The compounds indicated in Table 1 below were prepared in a similar way:

TABLE 1 physical data, H-NMR [δ, ppm] No. Example Melting point [° C.] 3

2.0(2H); 2.5(3H); 2.55(2H); 2.63(4H); 3.23(6H); 6.8(1H); 7.1(3H); 7.35(1H); 8.36(1H) 4

1.8(2H); 2.45(6H); 3.1(2H); 3.2(4H); 5.0(1H); 7.05(1H); 7.15(1H); 7.2(1H); 7.4(1H) 5

1.5(4H); 1.75(2H); 2.4(2H); 2.6(4H); 3.2(2H); 3.25(6H); 6.22(1H); 7.1(3H); 7.35(1H); 7.85(1H); 11.3(1H) 6

129-130 7

0.97(3H); 2.0-2.3(3H); 2.5(4H); 2.8(1H); 3.2(6H); 6.1 (1H); 6.85(2H); 7.07(1H); 7.2 (1H); 7.4(1H); 7.9(1H) 8

2.0(2H); 2.4(6H); 2.55(2H); 2.43(4H); 3.23(6H); 6.7(1H); 7.1(3H); 7.36(1H) 9

2.0(2H); 2.62(2H); 2.7(4H); 3.2(2H); 3.28(4H); 5.95(1H); 6.95(1H); 7.1 (3H); 7.35(1H); 8.55(2H); 10

1.95(2H); 2.5(2H); 2.6(4H); 3.15(2H); 3.27(4H); 4.87(2H); 6.15(1H); 7.1(3H); 7.35(1H); 8.06(1H) 11

1.75(4H); 2.45(2H); 2.62(4H); 3.22(6H); 6.98(1H); 7.1(3H); 7.35(1H); 8.5(2H) 12

1.98(2H); 2.55(2H); 2.65(4H); 3.25(6H); 6.21 (1H); 7.1(3H); 7.35(1H); 7.85(1H) 13

131-132 14

2.6(4H); 3.03(2H); 3.23(4H); 3.78(2H); 4.85(2H); 5.8(2H) 6.13(1H); 7.06(3H); 7.33(1H); 8.05(1H) 15

232-234 16

188-190 17

1.26(6H); 2.0(2H); 2.59 (2H); 2.66(4H); 2.88(1H); 3.2(6H); 6.2(1H); 6.78 (3H); 7.2(1H); 7.8(1H) 18

70-83 19

2.0(2H); 2.65(4H); 2.8(2H); 3.28(4H); 6.15(1H); 6.2(1H); 7.5(3H); 7.63(1H); 7.85(1H) 20

1.5(1H); 2(7H); 2.58(2H); 3.05(3H); 3.2(2H); 6.18(1H); 7.45(4H); 7.8(1H) 21

151-153 22

180-186 23

170-174 24

1.45(6H); 1.75(2H); 2.4(2H); 2.6(4H); 3.2(2H); 3.25(4H); 6.2(1H); 7.1(3H); 7.32(1H); 7.88(1H) 25

1.8-2.2(8H); 2.6(3H); 3.1(2H); 3.25(2H); 6.2(1H); 7.45(4H); 7.8(1H) 26

144-156 27

200-205 28

165-171 29

169-172 30

161-165 31

174-176 32

60-71 33

2.0(2H); 2.6(6H); 3.25(6H); 6.2(1H); 6.85(1H); 6.95(1H); 7.15(1H); 7.25(1H); 7.85(1H) 34

2.0(2H); 2.56(2H); 2.65(4H); 3.25(6H); 6.18(1H); 6.6(1H); 7.0(2H); 7.04(1H); 7.33(1H); 7.82(1H) 35

1.15(6H); 1.82(2H); 2.4(2H); 2.5(8H); 3.1(6H); 6.1(1H); 6.5 (1H); 6.58(2H); 7.85(1H) 36

1.3(18H); 2.0(2H); 2.55(2H); 2.65(4H); 3.25(6H); 6.2(1H); 6.8(2H); 7.0(1H); 7.85(1H) 37

38

151-153° C. 39

170-175° C. Hydrochloride 40

189-190° C. Hydrochloride 41

158-160° C. Hydrochloride 42

132-134° C. 43

44

118-125° C. 45

163-166° C. 46

109-114° C. 47

201-203° C. 48

138-140° C. 49

138-140° C. 50

77-80° C. 51

290-295° C. (Fumarate)

52

128-130° C. (Fumarate)

53

158-160° C. (Fumarate)

54

138-141° C. (Fumarate)

55

55-60° C. 56

62-70° C. 57

70-73° C. 58

127-134° C. Hydrochloride 59

85-90° C. 60

204-210° C. 61

137-191° C.

The compounds mentioned in Tables 2-6 below can obtained in a similar manner.

TABLE 2

Example No. R1 R2 R3 R6 R7 R8 R9 R10 X-Y A B 62 H H OH H tBut H Me H CH₂—N —CH₂— —(CH₂)₃— 63 H H OH H tBut H Ph H CH═C S —(CH₂)₃— 64 Me H OH H tBut H 1-Pyrrolyl H CH═C S —(CH₂)₃— 65 H H NH₂ H iProp H 2-Napht H CH═C S —(CH₂)₃— 66 H Me OH H Et H tBut H CH₂—N —CH₂— —(CH₂)₃— 67 H H OH OMe tBut H H H CH═C S —(CH₂)₃— 68 H H NH₂ OMe CF₃ H H H CH═C S —(CH₂)₃— 69 H H OH H CF₃ H tBut H CH₂—N —CH₂— —(CH₂)₃— 70 H H NHMe OiProp iProp H H H CH₂—N O —(CH₂)₄— 71 Me H OH H H CN tBut H CH₂—N —CH₂— —(CH₂)₃— 72 H H OH H H F tBut H CH═C S —(CH₂)₃— 73 H Me NH₂ H H Cl iProp H CH₂—N —CH₂— —(CH₂)₃— 74 H H NHMe H tBut H H OMe CH═C S —(CH₂)₃— 75 H H OH H iProp H H OMe CH₂—N —CH₂— —(CH₂)₄— 76 H H OH OMe tBut H tBut H CH═C S —(CH₂)₃— 77 H H OH OMe tBut H CF₃ H CH₂—N —CH₂— —(CH₂)₃— 78 Me H OH OMe CF₃ H tBut H CH₂—N O —(CH₂)₅— 79 H H NH₂ H nProp CN tBut H CH₂—N —CH₂— —(CH₂)₃— 80 H Me OH H CF₃ CN iProp H CH═C S —(CH₂)₃— 81 H H OH H Ph C═CH tBut H CH₂—N —CH₂— —(CH₂)₃— 82 H H NH₂ OMe tBut CN H H CH═C S —(CH₂)₃— 83 H H NHMe H tBut CN CF₃ OMe CH₂—N —CH₂— —(CH₂)₅— 84 H H OH OMe nProp F tBut H CH₂—N —CH₂— —(CH₂)₄— 85 H H OH H Ph CN tBut Me CH═C S —(CH₂)₃— 86 H H OH OMe tBut F H H CH₂—N —CH₂— —(CH₂)₃— 87 H H OH H tBut H Me H CH₂—N —CH₂— —CH₂—CH═CH—CH₂— 88 H H OH H tBut H Ph H CH═C S —CH₂—CH═CH—CH₂— 89 Me H OH H tBut H 1-Pyrrolyl H CH═C S —CH₂—CH═CH—CH₂— 90 H H NH₂ H iProp H 2-Napht H CH═C S —CH₂—C(CH₃)═CH—CH₂— 91 H Me OH H Et H tBut H CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂— 92 H H OH OMe tBut H H H CH═C S —CH₂—C(CH₃)═CH—CH₂— 93 H H NH₂ OMe CF₃ H H H CH═C S —CH₂—C(CH₃)═CH—CH₂— 94 H H OH H CF₃ H tBut H CH₂—N —CH₂— —CH₂—CH═CH—CH₂— 95 H H NHMe OiProp iProp H H H CH₂—N O —CH₂—CH═CH—CH₂— 96 Me H OH H H CN tBut H CH₂—N —CH₂— —CH₂—CH═CH—CH₂— 97 H H OH H H F tBut H CH═C S —CH₂—C(CH₃)═CH—CH₂— 98 H Me NH₂ H H Cl iProp H CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂— 99 H H NHMe H tBut H H OMe CH═C S —CH₂—C(CH₃)═CH—CH₂— 100 H H OH H iProp H H OMe CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂— 101 H H OH OMe tBut H tBut H CH═C S —CH₂—CH═CH—CH₂— 102 H H OH OMe tBut H CF₃ H CH₂—N —CH₂— —CH₂—CH═CH—CH₂— 103 Me H OH OMe CF₃ H tBut H CH₂—N O —CH₂—CH═CH—CH₂— 104 H H NH₂ H nProp CN tBut H CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂— 105 H Me OH H CF₃ CN iProp H CH═C S —CH₂—C(CH₃)═CH—CH₂— 106 H H OH H Ph C═CH tBut H CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂— 107 H H NH₂ OMe tBut CN H H CH═C S —CH₂—C(CH₃)═CH—CH₂— 108 H H NHMe H tBut CN CF₃ OMe CH₂—N —CH₂— —CH₂—CH═CH—CH₂— 109 H H OH OMe nProp F tBut H CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂— 110 H H OH H Ph CN tBut Me CH═C S —CH₂—C(CH₃)═CH₁₃CH₂— 111 H H OH OMe tBut F H H CH₂—N —CH₂— —CH₂—CH═CH—CH₂—

TABLE 3

Example No. R1 R2 R3 R7 R9 R10 X-Y A B 112 H H OH tBut Ph H CH₂—N —CH₂— —(CH₂)₃— 113 H H OH tBut 2-Napht H CH₂—N S —(CH₂)₃— 114 Me H OH tBut 1-Pyrrolyl H CH₂—N S —CH₂—CH═CH—CH₂— 115 H H NH₂ tBut cHex H CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 116 H H OH tBut nHex H CH₂—N S —(CH₂)₃— 117 H H OH tBut H OMe CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂— 118 H Me OH iProp H OMe CH₂—N S —CH₂—CH═CH—CH₂— 119 H H NH₂ H CH₃ OMe CH═C NH —(CH₂)₃— 120 H H OH H iProp OMe CH₂—N O —(CH₂)₃— 121 H H OH tBut H CH₃ CH₂—N S —CH₂—C(CH₃)═CH—CH₂— 122 H H OH tBut tBut OMe CH₂—N S —(CH₂)₃— 123 Me H OH tBut iProp OMe CH₂—N S —CH₂—CH═CH—CH₂— 124 H H NH₂ Ph tBut Cl CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 125 H H OH 2-Napht tBut Me CH₂—N S —(CH₂)₃— 126 H H OH tBut CF₃ OMe CH₂—N —CH₂— —CH₂—C(CH₃)═CH—CH₂—

TABLE 4

Example No. R1 R2 R3 R7 R8 R9 R10 X-Y A B 127 H H OH tBut H tBut H CH₂—N S —(CH₂)₃— 128 H H OH tBut CN H H CH₂—N S —(CH₂)₃— 129 Me H OH tBut H H OMe CH₂—N NH —CH₂—CH═CH—CH₂— 130 H H OH H CN tBu H CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 131 H H NH₂ CF₃ H tBut H CH₂—N S —(CH₂)₃— 132 H H OH nProp H iProp H CH═C —CH₂— —(CH₂)₃— 133 H Me OH H H iProp OMe CH═C S —(CH₂)₃— 134 H H OH tBut H tBut H CH₂—N NH —CH₂—CH═CH—CH₂— 135 H H OH tBut CN H H CH₂—N S —(CH₂)₄— 136 H H NH₂ tBut H H OMe CH₂—N O —(CH₂)₃— 137 Me H OH H CN tBu H CH═C S —CH₂—C(CH₃)═CH—CH₂— 138 H H OH CF₃ H tBut H CH₂—N —CH₂— —(CH₂)₃— 139 H H OH nProp H iProp H CH₂—N S —(CH₂)₃— 140 H H NHMe H H iProp OMe CH₂—N S —(CH₂)₃— 141 H H OH nProp CN tBut H CH₂—N S —(CH₂)₄— 142 H H OH CF₃ CN iProp H CH₂—N S —(CH₂)₃— 143 Me H OH Ph C═CH tBut H CH₂—N NH —CH₂—CH═CH—CH₂— 144 H H OH tBut CN tBut H CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 145 H H NH₂ tBut H nProp OMe CH₂—N S —(CH₂)₃— 146 H H OH Ph H tBut OMe CH═C —CH₂— —(CH₂)₅— 147 H Me OH CF₃ H tBut OMe CH═C S —(CH₂)₃— 148 H H OH tBut F H Me CH₂—N NH —CH₂—CH═CH—CH₂— 149 H H OH nProp CN tBut Me CH₂—N S —CH₂—CH═CH—CH₂— 150 H H NH₂ nProp C═CH tBut OMe CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 151 H H OH tBut CN H OMe CH₂—N S —(CH₂)₄—

TABLE 5

Example No. R1 R2 R3 R6 R8 R9 R10 X-Y A B 152 H H OH OMe H tBut H CH₂—N S —(CH₂)₃— 153 H H OH OMe H CF₃ H CH₂—N S —(CH₂)₃— 154 Me H OH OMe H tBut H CH₂—N NH —CH₂—CH═CH—CH₂— 155 H H OH H CN tBut H CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 156 H H NH₂ H F tBut H CH₂—N S —(CH₂)₃— 157 H H OH Me Cl iProp H CH═C —CH₂— —(CH₂)₃— 158 H Me OH H H iProp OMe CH═C S —(CH₂)₃— 159 H H OH H H tBut OMe CH₂—N NH —CH₂—CH═CH—CH₂— 160 H H OH CN H CF₃ H CH₂—N S —(CH₂)₄— 161 H H NH₂ H CN H OMe CH₂—N O —(CH₂)₃— 162 Me H OH H H tBu OEt CH═C S —CH₂—C(CH₃)═CH—CH₂— 163 H H OH H CN tBut H CH₂—N —CH₂— —(CH₂)₃— 164 H H OH Me H iProp H CH₂—N S —(CH₂)₃— 165 H H NHMe OMe H iProp H CH₂—N S —(CH₂)₃— 166 H H OH OMe CN tBut H CH₂—N S —(CH₂)₃— 167 H H OH OMe Me tBut H CH₂—N S —(CH₂)₃— 168 Me H OH H CN tBut OMe CH₂—N NH —CH₂—CH═CH—CH₂— 169 H H OH Me H tBut OMe CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 170 H H NH₂ H Cl CF₃ Me CH₂—N S —(CH₂)₃— 171 H H OH OMe CN tBut Me CH═C —CH₂— —(CH₂)₃— 172 H Me OH Me Me iProp Me CH═C S —(CH₂)₃—

TABLE 6

Example No. R1 R2 R3 R6 R7 R9 R10 X—Y A B 173 H H OH H tBut tBut H CH₂—N S —(CH₂)₃— 174 H H OH H tBut Ph H CH₂—N S —(CH₂)₃— 175 Me H OH H tBut 1-Pyrrolyl H CH₂—N NH —CH₂—CH═CH—CH₂— 176 H H OH H nPropyl tBut H CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 177 H H NH₂ H CF₃ tBut H CH₂—N S —(CH₂)₃— 178 H H OH H 2-Napth tBut H CH═C —CH₂— —(CH₂)₃— 179 H Me OH OMe tBut H H CH═C S —(CH₂)₃— 180 H H OH OMe iProp H H CH₂—N NH —CH₂—CH═CH—CH₂— 181 H H OH OMe H CF₃ H CH₂—N S —(CH₂)₄— 182 H H NH₂ H tBut H OMe CH₂—N O —(CH₂)₃— 183 Me H OH H iProp H Me CH═C S —CH₂—C(CH₃)═CH—CH₂— 184 H H OH CN tBut H H CH₂—N —CH₂— —(CH₂)₃— 185 H H OH H H CF₃ Me CH₂—N S —(CH₂)₃— 186 H H NHMe H nProp tBut H CH₂—N S —(CH₂)₃— 187 H H OH OMe tBut iProp H CH₂—N S —(CH₂)₄— 188 H H OH OMe CF₃ tBut H CH₂—N NH —CH₂—CH═CH—CH₂— 189 Me H OH Me tBut nProp H CH═C —CH₂— —CH₂—C(CH₃)═CH—CH₂— 190 H H OH Me tBut H OMe CH₂—N S —(CH₂)₅— 191 H H NH₂ OMe tBut tBut OMe CH═C —CH₂— —(CH₂)₃— 192 H H OH Me CF₃ tBut OMe CH═C S —(CH₂)₃—

Examples of Pharmaceutical Forms

A) Tablets Tablets of the followwing composition are com- pressed in a tabletting machine ina conventional manner 40 mg of substance of Example 1 120 mg of corn starch 13.5 mg of gelatin 45 mg of lactose 2.25 mg of Aerosil ™ (chemically pure silica in sub- microscopically fine dispersion) 6.75 mg of potato starch (as 6% strength paste) B) Sugar-coated tablets 20 mg of substance of Example 4 60 mg of core composition 70 mg of sugar-coating composition

The core composition comprises 9 parts of corn starch, 3 parts of lactose and 1 part of vinylpyrrolidone/vinyl acetate 60:40 copolymer. The sugar-coating composition comprises 5 parts of sucrose, 2 parts of corn starch, 2 parts of calcium carbonate and 1 part of talc. The sugar-coated tablets produced in this way are subsequently provided with an enteric coating.

Biolocrical Investigations—Receptor-binding Studies

1) D₃ Binding Assay

Cloned human D₃ receptor-expressing CCL 1.3 mouse fibroblasts obtained from Res. Biochemicals Internat. One Strathmore Rd., Natick, Mass. 01760-2418 USA, were used for the binding studies.

Cell Preparation

The D₃-expressing cells were grown in RPMI-1640 containing 10% fetal calf serum (GIBCO No. 041-32400 N); 100 U/ml penicillin and 0.2% streptomycin (GIBCO BRL, Gaithersburg, Md., USA). After 48 h, the cells were washed with PBS and incubated with 0.05% trypsin-containing PBS for 5 min. Neutralization with medium was then carried out, and the cells were collected by centrifugation at 300×g. To lyze the cells, the pellet was briefly washed with lysis buffer (5 mM tris-HCl, pH 7.4, with 10% glycerol) and then incubated in a concentration of 10⁷ cells/ml of lysis buffer at 4° C. for 30 min. The cells were centrifuged at 200×g for 10 min and the pellet was stored in liquid nitrogen.

Binding Assays

For the D₃ receptor-binding assay, the membranes were suspended in incubation buffer (50 mM tris-HCl, pH 7.4, with 120 mM NaCl, 5 mM KCl, 2 mM CaCl₂, 2 mM MgCl₂, 10 μM quinolinol, 0.1% ascorbic acid and 0.1% BSA) in a concentration of about 10⁶ cells/250 μl of assay mixture and incubated at 30° C. with 0.1 nM ¹²⁵iodosulpiride in the presence and absence of test substance. The non-specific binding was determined using 10⁻⁶ M spiperone.

After 60 min, the free and the bound radioligand was separated by filtration through GF/B glass fiber filters (Whatman, England) on a Skatron cell collector (Skatron, Lier, Norway), and the filters were washed with ice-cold tris-HCl buffer, pH 7.4. The radioactivity collected on the filters was quantified using a Packard 2200 CA liquid scintillation counter.

The K_(i) values were determined by non-linear regression analysis using the LIGAND program.

2) D₂ Binding Assay

Membrane Preparation

a) Nucleus Caudatus (Bovine)

Nucleus caudatus was removed from bovine brain and washed in ice-cold 0.32 M sucrose solution. After determination of the weight, the material was comminuted and homogenized in 5-10 volumes of sucrose solution using a Potter-Evehjem [sic] homogenizer (500 rpm). The homogenate was centrifuged at 3,000×g for 15 minutes (4° C.), and the resulting supernatant was subjected to another 15-minute centrifugation at 40,000×g. The residue was then washed twice, by resuspension and centrifugation, with 50 mM tris-HCl, pH 7.4. The membranes were stored in liquid N₂ until used.

b) Striatum (Rat)

Striati from Sprague-Dawley rats were washed in ice-cold 0.32 M sucrose solution. After determination of the weight, the parts of the brain were homogenized in 5-10 volumes of sucrose solution using a Potter-Elvehjem homogenizer (500 rpm). The homogenate was centrifuged at 40,000×g for 10 minutes (4° C.), and then the residue was washed several times, by resuspension and centrifugation, with 50 mM tris-HCl, 0.1 mM EDTA and 0.01% ascorbic acid (pH 7.4). The washed residue was resuspended in the abovementioned buffer and incubated at 37° C. for 20 minutes (to break down the endogenous dopamine). The membranes were then washed twice with buffer and portions were frozen in liquid nitrogen. The membrane prepration [sic] was stable for a maximum of 1 week.

Binding Assay

a) ³H-Spiperone (D_(2low))

Nucleus caudatus membranes were taken up in incubation buffer (mM: tris-HCl 50, NaCl 120, KCl 5, MgCl₂ 1, CaCl₂ 2, pH 7.4). Various mixtures, each of 1 ml, were prepared:

Total binding: 400 μg of membranes+0.2 mmol/l ³H-spiperone (Du Pont de Nemours, NET-565).

Non-specific binding: as mixtures for total binding+10 μM (+)-butaclamol.

Test substance: as mixtures for total binding+increasing concentrations of test substance.

After incubation at 25° C. for 60 minutes, the mixtures were filtered through GF/B glass fiber filters (Whatman, England) on a Skatron cell selector (from Zinsser, Frankfurt), and the filters were washed with ice-cold 50 mM tris-HCl buffer, pH 7.4. The radioactivity collected on the filters was quantified using a Packard 2200 CA liquid scintillation counter.

The K_(i) values were determined by non-linear regression analysis using the LIGAND program or by conversion of the IC₅₀ values using the formula of Cheng and Prusoff.

b) ³H-ADTN (D_(2high))

Striatum membranes were taken up in incubation buffer (50 mM tris-HCl, pH 7.4, 1 mM MnCl₂ and 0.1% ascorbic acid).

Various mixtures, each of 1 ml, were prepared.

Total binding: 300 μg wet weight+1 nM ³H-ADTN (Du Pont de Nemours, customer synthesis)+100 nM SCH 23390 (occupation of D1 receptors).

Non-specific binding: as mixtures for total binding+50 nM spiperone.

Test substance: as mixtures for total binding+increasing concentrations of test substance.

After incubation at 25° C. for 60 minutes, the mixtures were filtered through GF/B glass fiber filters (Whatman, England) on a Skatron cell selector (from Zinsser, Frankfurt), and the filters were washed with ice-cold 50 mM tris-HCl buffer, pH 7.4. The radioactivity collected on the filters was quantified using a Packard 2200 CA liquid scintillation counter.

The evaluation took place as under a).

In these assays, the compounds according to the invention show very good affinities and high selectivities for the D₃ receptor. The results for representative compounds are compiled in the following Table 7.

TABLE 7 Receptor binding D₃ D₂ Example ¹²⁵I-sulpiride ³H-spiperone Selectivity No. K_(i) [nM] K_(i) [nM] K_(i) D₂/K_(i)D₂ 12 4.2 357 85 13 2.3 142 61 17 2.8 200 71 19 3.0 175 58 48 4.0 480 120  

We claim:
 1. A pyrimidine compound of formula I

wherein A is C₂-C₁₅-alkylene which is interrupted by, or which is bonded to the pyrimidine ring through, a radical NR⁴, B is

R¹, R², R³ are, independently of one another, H, halogen, OR⁴, NR⁴R⁵, SR⁴ CF₃, CN, CO₂R⁴ or C₁-C₈-alkyl which is unsubstituted or substituted by OH, OC₁-C₈-alkyl or halogen, R⁴ is H, C₁-C₈-alkyl which is unsubstituted or substituted by OH, OC₁-C₈-alkyl or halogen, R⁵ has the meanings indicated for R⁴ or is COR⁴ or CO₂R⁴, Ar is pyridyl, pyrimidyl, triazinyl, naphthyl or quinolinyl, where Ar may carry from one to four substituents selected from the group consisting of OR⁵, C₁-C₈-alkyl, C₂-C₆-alkenyl, C₂-C₆-alkynyl, halogen, CN, CO₂R⁴, NO₂, SO₂R⁴, SO₃R⁴, NR⁴R⁵, SO₂NR⁴R⁵, SR⁴, CF₃, CHF₂, pyrrolyl and pyrrolidinyl, or a salt thereof with a physiologically tolerated acid.
 2. The pyrimidine compound of formula I defined in claim 1, where Ar is pyridyl, pyrimidyl, triazinyl, naphthyl or quinolinyl, where Ar may carry one or two substituents X and Y selected from the group consisting of OR⁵, C₁-C₈-alkyl, halogen, CN, CO₂R⁴, NO₂, SO₂R⁴, SO₃R⁴, NR⁴R⁵, SO₂NR⁴R⁵, SR⁴, CF₃, CHF₂, and or a salt thereof with a physiologically tolerated acid.
 3. The pyrimidine compound of formula I defined in claim 1, where A is C₃-C₁₀-alkylene which is interrupted by, or which is bonded to the pyrimidine ring through the radical NR⁴, or a salt thereof with a physiologically tolerated acid.
 4. The pyrimidine compound of formula I defined in claim 1, where R¹, R² and R³ are, independently from one another, H, C₁-C₈-alkyl, which may be unsubstituted or substituted by OH, OC₁-C₈-alkyl or halogen, or OH, OC₁-C₈-alkyl, SR⁴ or NR⁴R⁵ where R⁴ and R⁵ are, independently of one another, H or C₁-C₈-alkyl; Ar is pyridyl or pyrimidyl, where Ar may carry one to four substituents selected from the group consisting of C₁-C₈-alkyl, or OR⁵ where R⁵ is H, C₁-C₈-alkyl, which may be unsubstituted or substituted by OH, OC₁-C₈-alkyl or halogen, or CF₃, CHF₂, halogen, C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₅-C₆-cycloalkyl, phenyl, or a salt thereof with a physiologically tolerated acid.
 5. The pyrimidine compound of formula I defined in claim 4, where B is

or a salt thereof with a physiologically tolerated acid.
 6. The pyrimidine compound of formula I defined in claim 4, where R¹ is H, C₁-C₈-alkyl which is unsubstituted or substituted by OH, OC₁-C₈-alkyl or halogen, or OR⁴, SR⁴ or NR⁴R⁵ where R⁴ and R⁵ are, independently of one another, H or C₁-C₈-alkyl, R² is H, OR⁴ or C₁-C₈-alkyl, and R³ is H, or a salt thereof with a physiologically tolerated acid.
 7. The pyrimidine compound of formula I defined in claim 1, where Ar is pyridinyl which may carry from one to four substituents selected from the group consisting of C₁-C₈-alkyl, phenyl, OH, OC₁-C₈-alkyl, halogen, CF₃, CN, C₂-C₆-alkenyl and C₂-C₆-alkynyl, or a salt thereof with a physiologically tolerated acid.
 8. The pyrimidine compound of formula I defined in claim 1, where Ar is pyrimidinyl which may carry from one to three substituents selected from the group consisting of C₁-C₈-alkyl, phenyl, C₅-C₆-cycloalkyl, OH, OC₁-C₈-alkyl, halogen, CN, NO₂, CF₃, CHF₂, and SO₂R⁴ or SR⁴ where R⁴ is H or C₁-C₈-alkyl, or a salt thereof with a physiologically tolerated acid.
 9. The pyrimidine compound of formula I defined in claim 8, where Ar is

 wherein X and Y are, independently of one another, selected from the group consisting of C₁-C₈-alkyl, or phenyl, pyrrolyl, CN, NO₂, CF₃, CHF₂, OC₁-C₈-alkyl, halogen, SO₂R⁴ or SR⁴ where R⁴ is H or C₁-C₈-alkyl, or a salt thereof with a physiologically tolerated acid.
 10. The pyrimidine compound of formula I defined in claim 9, where X and Y are, independently of one another, selected from the group consisting of C₁-C₈-alkyl, CF₃ and CHF₂, or a salt thereof with a physiologically tolerated acid.
 11. The pyrimidine compound of formula I defined in claim 8, where B is

or a salt thereof with a physiologically tolerated acid.
 12. The pyrimidine compound of formula I defined in claim 8, where R¹, R² and R³ are independently selected from H, C₁-C₈-alkyl, or OR⁴, wherein R⁴ is H or C₁-C₈-alkyl, or a salt thereof with a physiologically tolerated acid.
 13. A process for preparing the compound of claim 1, which comprises i) reacting a compound of formula II:

where Y¹ is a suitable leaving group, with a compound of formula III H—B—Ar  (III) ii) to prepare a compound of formula I′ where A is interrupted by or is bonded to the pyrimidine ring through NR⁴: reacting a compound of formula:

 where R^(1a) is OH, R^(2a) and R^(3a) are, independently of one another, H, C₁-C₆-alkyl, OC₁-C₆-alkyl, SC₁-C₆-alkyl, CO₂H, OH, NR⁴R⁵ or halogen, where R⁴ and R⁵ are H or C₁-C₆-alkyl, Z^(1a) is NHR⁴ and A¹ is C₀-C₁₅-alkylene, with a compound of formula VI: Y¹—A²—B—Ar  (VI) where Y¹ is a suitable leaving group, and A² is C₁-C₁₅-alkylene, where A¹ and A² together have 2 to 15 carbon atoms.
 14. A pharmaceutical composition comprising the compound of formula I defined in claim 1 with or without physiologically acceptable vehicles and/or ancillary substances.
 15. A method of treating schizophrenia, depression, neuroses and psychoses which respond to dopamine D₃ ligands, which comprises administering a therapeutically effective amount of the pyrimidine compound of formula I defined in claim 1 or its salt with a physiologically tolerated acid to a person requiring such treatment. 